In article ,
"Pete KE9OA" wrote:

Snip

Now, another point comes into consideration..............close-in IP3
performance. Three major mechanisms affect this parameter. First of
all, the performance of the 2nd mixer itself. Most receivers use a
"weaker" 2nd mixer since the roofing filter protects this device from
out of band signals. If a stronger 2nd mixer with better IMD
performance is used, the close-in IMD will improve.

Snip

Every stage in the radio that the signal has to pass through will add
its own set of intermodulation products. RF amplifiers, RF attenuators,
all and any mixers, IF amplifiers, filters, and demodulators.

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Telamon
Ventura, California